Mechanical seals are frequently used in high temperature environments to separate fluids of different kinds. One form of high temperature seal is known as the bellows-type seal, i.e., a seal in which an expansible bellows is used. High temperature uses of mechanical seals dictate high temperature resistant gaskets retained and highly compressed between various parts by the use of bolts. These are in lieu of the more conventional rubber O-ring seals. Some of the more common gasket materials are those containing carbon, graphite, asbestos and/or fiberglass, i.e., fragile materials characterized by poor elasticity and conformability. In the absence of provisions for high clamping forces, the conventional gasket of such materials is precision formed with gasket surfaces and cross-sections matching the surfaces and cross-sections of their receiving cavities. By their very nature, such materials cannot readily be made to the degree of precision required to provide a leak-tight fit by close or precision fit alone, so that high clamping forces are required to perfect the seals. As can be readily understood, the known gaskets are relatively expensive because of their method of manufacture and have little ability to seal over even very slight surface flaws. And the product must be constructed to permit the requisite clamping forces.